Fróðskaparrit - 01.01.2004, Síða 222

220 ALTITUDINAL DISTRIBUTION OF PLANT COMMUNITIES IN THE FAROE ISLANDS
Table 1. Details of tlie ftve investigated transects.
Name of locality Latitude Longitude Length (km) Altitude (m u.s.l.) Aspeet
1 Somfelli 62°04'I0" N 6=57'25 "W 3.7 749 N
2 Mosarøkur 62° 11 "05" N 7°10'52"W 4.0 756 SW
3 Ørvisfelli 62°12'32"N 7°09'17"W 1.2 783 N
4 Gráfelli 62°18'41 "N 6°59'48"W 2.9 856 sw
5 Villingardalsfjall 62°22'53"N 6°33'13"W 1.3 841 s
Lawesson et al., 2003). The pH increases
with altitude with a minimum value of 4.8
at low altitudes and a maximum value of 5.8
at high altitudes (Olsen and Fosaa, 2002).
This is a result of a more humus-rich soil in
the lowlands and a less acid mineral soil at
higher altitudes. Vegetation cover also de-
creases with altitude (Fosaa, 2004).
Sampling
In July-August 1999 and 2000, the vegeta-
tion on five mountains in the Faroe Islands
was investigated along five transects, from
the highest elevation (856 m a.s.l.) down to
an elevation of 150 m a.s.l. (Fig. 1). Two
of the mountains have north-facing aspects,
one has a south-facing aspect and two have
southwest-facing aspects. Both the south-
facing and southwest-facing aspects will
be referred to as south-facing aspects in
the text. Table 1 lists details about loca-
tion, length of transect, altitude (m a.s.l.),
and the aspects of the five transects. Here
we can see that the length of the transects
varies from a long transect (4.0 km) with
a gentle slope to a short transect (1.2 km)
with a steep slope along its whole length.
A total of 538 plots were sampled on the
five mountains. The vegetation was sam-
pled in 50 m altitudinal intervals from 100
m2 quadrats (macro-plots). In each macro-
plot, 8 smaller (0.25 m2) quadrats (meso-
plots) were placed randomly. The meso-
plots were subdivided into 25 (0.0 lm2)
micro-plots and the presence/absence of
each plant species was noted for each mi-
cro-plot. In this way, the abundance of spe-
cies, ranging from 1 to 25, was determined
for each meso-plot.
In each meso-plot, one soil core, 5 cm in
diameter and 10 cm deep, was sampled after
the top vegetation layer had been removed.
The pH, measured with a Radiometer PHM
240, was determined after placing the soil
sample in distilled water. The vegetation
cover was estimated as percentage cover-
age for each meso-plot and the slope was
measured in degrees.
The nomenclature of Jóhansen et al.
(2000) was used for vascular plants; of
Smith (1978) for bryophytes; and of Pur-
veys et al. (1992) for lichens.
Data analysis
The vegetation data were analysed by the
computer programme MVSP, using ag-
glomerative hierarchical techniques (Ko-
vach, 1986-1999). Minimum variance and
squared Euclidean distance were adopted
to calculate the variance between pairs. The
analysis included 538 samples and 165 taxa
of vascular plants, lichens and bryophytes.